Photoelectric tube



Aug. 5, 1941. BERG, JR 2,251,653

PHOTOELECTRIC TUBE' Filed March 25, 1937 INVENTOR %mi, kw WM ATTORNEYS Patented Aug. 5, 1941 1 QFF ICE rnorosrnornio'ronn HenryA, Berg 11%., Pittsburgh, Pa. Application March 25, 1937,1Sria1 Nor-1329 65 some; (o1. 250%1613) My invention relates to photo-electric tubes; and consists in improvements and refinements in structure.

In application forlLetters Patent Serial No. 127,867Qfiled Febffiai'y 2c; '1'es7,'i1ow Patent No; 2,219,976} dated "October 29,1940, I'illustrate and describe apparatus 'rar automatically "condoning the head lights 'of mama-leaf sueh appa atus essentially includes a photo-seems tube that is installed in anautornob-il in such positionasto' receive light from the headlight'beamsbf cars. approaching in opposite direction; 'Under the temporary iniluencelof such light beams, the photo-electric ,tubein known 'way is adapted to modify the electric conditions ofja momma such manner that an energizing current fiows'through one or more electric re lays, or other circuit-controlling devices. The energized relays, or other ancer r r n e o fiet aut at the temporary dimming or deflecting of the lightbeam i h e d ts Q ths af q i p ql i eap ara us .l .l Y I s rs u v within e tiqn I Pro ide a photoelectric tube which is particularly, though n l ivela. r ned. c rf w r pe i ashr paratus. I provide my improvements in the construction of phot-o-electrio tubes, with the followingobjects, among others, in View; 7 i i T ube h be. o i creas d me, anic l st en th.- I Q 7 (2) That the tubeshall' withgreater sensitivity r sp nd o. li t-b a n t; n beams tha a ected, u n h t be o m d ect q bu so eams th pl u o he tu a nsg a u-ia the manner that the headlight beams.atone car l y v r mslansle m mo n: the. indsh eld of a her ar hat p oache nd. ss s l he. h a r r 1 '7 3 hat he aL e mu e ower e owidi rr char e of th tu e ,sba l-r es lv u g cess d. h the um nati n there??? ribe be s/lo t an p r c an pas ac r) is e mm bed so that the apparatusshallbe more quickly 1 esponsive to conditions of service v a gisavi v inside elevation and partly in axial sec.- a photo-electric tube-embodying thein In the accompanying dra pa t tion, of vention.

Fig. II is a fragmentary View in particular anode element embodied in my tube.

Fig. III is a viewjn plan oi a suppressor gridv which is interposed between the anode and catheasements of the tube. V X f f Fig. IV is a viewin plan oithe cathode element q f n t gq H r .l .l 7.

nianner in the base of the bulb; In accordance with known practice a metal contact ring, I I0 is secured upon the base of the assembled stern and bulb; and mountedin such base, in electric isolation from the' contact ring I lo and from one another,'ar eftwo contact prongs Ma and lib; As

will presently appear, the ring Ho and prongs I la and"! lb are severally connected'to the photo' electric elements included in 'the bulb, and in known way the assembled structure is adapted to be mounted in a supporting socket (not shown) in whichthe"ring" H'c and prongs Ho and Nb engage'c'on plementary contactelements and seve'rally f complete". electrical connections between the' photoeelectric elements in; the bulb and certain circuit Wires of the apparatus to be operated.

In-accordance" with my invention, each of the essentialj anode" and cathodeelementslfi and 11, respectively; of the photo-electric tube extends in a plane that'i's normal to the axis of the bulb H. The atmosphere within the bulb may be any suitable oneof the known gases or gaseous mixtures now used, although I prefer an inert atmosphere of "helium. The anode and cathode elementsdiand' l1 arespaced apart axially of the' bulb within" which they 'are 'sealed, and between such elements I interpo'se a suppressor grid 18;

The cathode l'lcomprises a dish-shaped member offthin sheet copper, integrally mounted on the upper" ends of two supporting rods 89, with its dished fface directed towards the end-wall 1 la of thegglasfs bulb or; envelope. The rods are formed-{as usual, of metal of high electric conductivity and, as usual, the lower body portions of therods are sealed and rigidly supported in tlf e glass body of the stem 12. At least one, if

not,;both,pof-the rods extends through the stem 1Z',"and within the basal portion of the assembled tube is welded or soldered to the contact prong lib. The dished face of the copper cathode TI is coated with a light-sensitive material. More specifically, the dished surface of the copper cathode is in known Way'o'xidized, and a film of' caesium applied to the cuprous oxide; Alternately, and in further refinemenathe cathode may be providedfirst with a coating or plating of metallic silver, and the silver coating oxidized,

before the surface of the cathode is sensitized inv usual way in 'th'e presence of caesium vapor (or other suitable alkali vapor).

transverse section of the The anode It consists of a fine mesh, circular screen of metal Wire, say a fine wire of nickel, the size of wire and mesh being shown on exaggerated scale in the drawings. It will be perccived that the diameter of the sccreen 16 (Fig. I) is less than that of the dished cathode Tl, so that the periphery of the screen lies within the compass of the upturned edge Tia of the cathode. In assembly, the anode it is soldered or otherwise electrically and mechanically integrated, as at 14 and E5, to the upper ends of two metal supporting rods 8%, that extend downward through the floor of the cathode Ti and are sealed in the glass stem I2. Within the base of the tube structure, the electrically conductive metal rods 8| are united to the contact prong Ha.

The suppressor grid 78 consists in a relatively small circular screen of fine mesh wire, such as the wire of which the anode i6 is made, and is soldered, or otherwise integrated to the upper end of a metal supporting rod l9. This supporting rod, as the rods 8! already described, extends through the fioor of the cathode TI, and is rigidly integrated with and sealed in the body of glass stem "l2, and within the base of the tube assembly such rod l'il is electrically united with the contact sleeve lie.

It will be understood that the rods 19 and 8| are electrically insulated from the cathode 11 through which they extend. Advantageously, tubular insulators 82 and 83 are provided for insulating the rods from the cathode, and for mechanically reinforcing and strengthening the assembly of elements 16, T1, and 18 within the bulb ii. As shown in the drawing, these insulators may be formed of glass, or other suitable electrical non-conductive material, which is molded and firmly integrated with the floor of the cathode, such floor being initially perforated to receive the insulators, as indicated in Fig. V. Thus, within the glass bulb or envelope H, the anode lb and cathode ll, spaced apart axially of the tube structure H, are mounted in sturdy assembly, with the suppressor grid 18 interposed between. The supporting rods 80 electrically connect the cathode Tl to the contact prong llb; the rods 81 connect the anode 15 to the contact prong II a; and the rod 19 connects the grid 18 to the contact ring lie. And it is important to note that the several photo-electric elements 16, TI, and E8 lie in spaced-apart planes which extend normal to the axis of the tube structure. Manifestly, by virtue of the recticulated or meshed structure of the anode l6 and grid 18, these elements readily permit the passage of light. They may be said to be light pervious.

The theory of operation of photo-electric tubes is well-known in the art, and sumce it to say herein that when a suitable electric potential is applied across the anode and cathode, and the cathode 77 within the tube l I is illuminated there is an electronic flow from the cathode to the anode element within the tube, in consequence of which an electric current is caused to flow through an external circuit connected to such elements, to effect the operation of associated electric instrumentalities. In the case in mind such electric instrumentalities comprise means for deflecting or dimming the headlight beams of an automobile.

In my structure the grid element 78 may be connected to negative side of a power supplying circuit, and in the operation of the photo-electric tube the grid 18 serves a dual purpose. First: When the photo-electric tube is subjected to light, the grid element serves to accelerate the electronic flow from the cathode to the anode. This acceleration in electronic flow increases the power of the tube, and renders its operation more quickly responsive to illumination. Second: When such illumination of the tube is terminated, the electronic flow from cathode to anode tends to continue, due to the conductivity of the gas in the tube, so that photo-currents continue to fiow in the external circuits, and continue to effect operation (operation of headlight-deflecting or dimming apparatus in this case) for a longer interval than is desired. This undesired, continuing electronic flow, known in the art as glow discharge and fringe discharge, is harmful to, and shortens the life of, the tube. In my structure the grid element both suppresses this undesired electronic flow and attracts the flow toward itself, thereby minimizing the danger of damage to the tube, and insuring a longer effective life of the cathode.

In gaining these ends, I have found that it is desirable, if not essential, to arrange the suppressor grid 18 concentrically of the cathode and between the anode and the cathode. The area of the suppressor grid equals from 25% to 33%% of the efiective area of the anode, so that the grid does not control the entire electronic flow within the tube, but chiefly control the glow discharge which has its inception at the center of the anode. The grid is removed from the usual fringe discharge of electrons that emanates from the peripheral portion of the cathode.

In further accordance with the invention, I provide an electrical canopy for inhibiting, or neutralizing the efiect of, the electronic fringe discharge of the tube. This canopy may consist, as shown in this case, of a jacket or coating 84 of electric conductive material upon the side wall of the glass bulb II. This jacket may consist in a sprayed-on coating ocf silver or other metal of high conductivity, and, as shown in Fig. I, the jacket entirely covers the side wall of the glass bulb or envelope, extending from above the assembled anode and cathode within, down to and into electric communication with the contact ring 0. Indeed, the jacket 84 may be applied beforev the contact ring I la is assembled upon the base of the tube. In service, the fringe discharge of the tube is attracted by the jacket 84 and lead to the same contact terminal (I la) that is connected to the suppressor grid 18. By virtue of such structure, advantages of the nature indicated are obtained.

I claim as my invention:

1. A photo-electric tube including a glass envelope having therein a light-pervious anode, a cathode coated with a photo-electrically sensitive material, means supporting said anode and cathode in closely spaced relation, an inert atmosphere in said envelope, an electronic-glowdischarge-suppressing grid supported in position between said anode and cathode, and an electronic-fringe-discharge-suppressing band of electro-conductive material spaced from and extending in encompassing relation with respect to the peripheries of the assembled anode, cathode and grid.

2. A photo-electric tube including a glass envelope having therein a cathode, saidcathode comprising a dished member having an upstanding peripheral rim, said member coated on its dished surface with a photo-electrically sensitive material, an anode comprising a light-pervious disk of electro-conductive material included in said envelope, the periphery of the anode disk extending in proximity to the edge of the upstanding peripheral rim of the dished cathode, and a support tructure within said tube mechanically integrating the anode and cathode in isolation with respect to conductive electrical currents.

3. A photo-electric tube including a glass envelope having supported therein a cathode, said cathode comprising a dished member having an upstanding peripheral rim, said member coated on its dished surface with a photo-electrically sensitive material, an anode comprising a lightpervious disk of electro-conductive material supported in said envelope in closely spaced relation with respect to the dished surface of said cathode, and an electronic-glow-discharge-suppressing grid supported within the compass of the upstanding rim of said cathode and between the cathode and anode and in electrically conductive isolation from both cathode and anode.

4. A photo-electric tube including a glass envelope having therein a light-pervious anode and a cathode, an inert atmosphere in said envelope, said cathode comprising a disk-like body coated with a photo-electrically sensitive material, said disk-like body of the cathode including a perforation, an insulator secured in said perforation, and a member connected to the anode and extending through said insulator, said structure providing mutual reinforcement of the assembled anode and cathode and providing a support therefor, with mechanical integration and electrical-conductive isolation of said anode and cathode.

5. A photo-electric tube structure including a glass envelope having therein a light-pervious anode, a cathode, and a grid between said anode and cathode, an inert atmosphere in said envelope, said cathode comprising a disk-like body coated with a photo-electrically sensitive material, a support for said cathode in the tube, the disk-like body of the cathode having two insulators secured thereto and extending therethrough, and two members anchored to the tube structure and extending severally through said two insulators and secured severally to said anode and to said grid, providing mutual reinforcement of the assembled anode, cathode and grid.

6. A photo-electric tube structure including a light-pervious anode and a cathode in an inert atmosphere within an envelope, said cathode comprising a disk-like body coated with a photoelectrically sensitive material, a support for said cathode in the envelope, the disk-like body of the cathode including two perforations, two insulators severally positioned in said perforations, and two rods anchored to the tube structure and extending severally through said insulators and supporting said anode securely in closely spaced relation with respect to said cathode, a grid positioned between said anode and cathode, said grid being of relatively small area with respect to said cathode, said cathode including a third perforation, with an insulator positioned in said third perforation, and means including said last insulator securing said grid in such position between the anode and cathode.

HENRY A. BERG, JR. 

